In this double blinded randomized study we evaluate effect of Zinc sulfate for prevention mucositis due to high dose chemotherapy in the patients undergoing bone marrow transplantation whose received Busulfan and/or Cyclophosphamide. Patients randomized in two groups: intervention and control with balanced block randomization method. Intervention group received Zinc sulfate immediately after start conditioning regimen and continued for two weeks. Control group received placebo at the same manner. Prevalence and severity of mucositis will be compared in two groups.